The present invention is related to conformal antenna and, more particularly, is directed towards very thin wrap-around antennas which are capable of being mounted on almost any surface contour.
Space limitations and size requirements often are deemed critical in many antenna applications, especially when they are mounted on the noses or cylindrical bodies of projectiles. These antenna must have low profiles to prevent drag, must be rugged enough to withstand harsh temperature and velocity environments, and yet must provide the desired radiation pattern. Conformal antennas which can be flush mounted to the exterior of a variety of surface contours provide a solution when such considerations are of importance. They also can be mounted on various projectiles with little or no modification to the projectile structure.
Conformal antennas, themselves, are not new to the antenna art. U.S. Pat. No. 3,475,755 to Bassen et al. discloses one approach to wrap-around mounting, the ring antenna. It comprises a dielectric ring having an inner copper cladded surface acting as the ground plane and a conducting strip open at one end and connected to the ground plane at the other. This antenna is fed directly through a hole in the dielectric ring by the center conductor of a rigid coaxial cable to a proper impedance point on the ring. This places restrictions both on the location of the feed point and the thickness of the ring itself.
Another form of an antenna adapted to be wrapped around the circumference of a missile is taught by Krutsinger et al. in U.S. Pat. No. 3,810,183. Again the antenna includes inner and outer radially spaced copper clad conductors which define a pair of paralled plates one-half wavelength long. It radiates in a microstrip mode where the instantaneous electric field at one end of the rectangular plate is oppositely directed to that at the other end of the parallel plates. The half wavelength plate is excited with a short probe placed at a high impedance point and thus requires a complex impedance matching network required for a standard 50 ohm input transmission line.
Prior conformal antennas, because of their design configuration, therefore have drawbacks which often limit their application. It is the development of a conformal antenna which overcomes these drawbacks to which this invention is directed.